Pulse plating of Pt on n-GaAs (100) wafer surfaces: Synchrotron induced photoelectron spectroscopy and XPS of wet fabrication processes

摘要

Preparation steps of Pt-GaAs Schottky contacts as applied in the fabrication process of varactor diode arrays for THz applications are analysed by photoelectron spectroscopy. Pulsed cathodic deposition of Pt onto GaAs (1 00) wafer surfaces from acidic solution has been studied by core level photoelectron spectroscopy using different excitation energies. A laboratory AlKα source as well as synchrotron radiation of hv = 130 and 645 eV at BESSY was used. Chemical analyses and semiquantitative estimates of layer thickness are given for the natural oxide of an untreated wafer surface, a surface conditioning NH_3 etching step, and stepwise pulse plating of Pt. The structural arrangement of the detected species and interface potentials are considered.